Protein Binge No Help In Pumping Up Muscles

The lure of protein as a builder of muscles and a source of vitality dates back to the early Greeks, who believed that meat automatically made muscle. Such exaggerated expectations, now fueled by overblown advertising slogans, linger to this day.

Meat builds muscle no more automatically than the protein in grains or vegetables. Eating excess protein from whatever source offers no advantage, since the body has no way to store it. Contrary to popular belief, it does not just make more muscle. Excess calories, whether from carbohydrate, fat, protein or alcohol, will simply be burned as fuel or, if energy needs have been met, converted to fat.

Eating enough protein every day is certainly important. Next to water it is the largest component of our cells. Proteins are necessary to build and repair body tissues, transport essential metabolites, and regulate and catalyze biological reactions. They are part of the carpentry that helps keep the body erect, the glue that holds cells together, and the machinery that makes the whole thing work.

We need enough protein on a daily basis to replace the inevitable losses in urine, sweat and in the continual sloughing off of cells from the skin and the digestive tract. For adults, the National Academy of Sciences' Recommended Dietary Allowance (RDA) is 0.8 grams of proteinkilogram (kg.) of body weight, assuming a mixed protein diet from both animal and vegetable sources. This translates to about 56 grams (almost 2 ounces) of protein per day for the average 154-pound man, and 44 grams (1 1/2 ounces) for an adult woman weighing about 120 pounds.

Pregnancy, lactation and periods of childhood growth call for extra protein to support the increased synthetic processes. Requirements also rise during infections and fevers, and following surgery.

Our need for protein is really a need for amino acids, the building blocks of proteins, which are chained together in long necklaces by special molecular links called peptide bonds. During digestion, food proteins are broken down by the addition of one molecule of water across each peptide bond. Amino acids are then absorbed from the small intestine into the bloodstream, carried throughout the body and reassembled into human protein according to the needs of each cell.

When we talk about protein quality, we refer to the proportion of essential amino acids in the protein. Nine amino acids are dietary ''essentials'' for humans and for most of the animal kingdom. They are termed essential because the body cannot synthesize them or, during certain periods of life, cannot make them rapidly enough.

Protein of high quality, like that found in meat, milk and eggs, contains the essential amino acids in optimal proportions to support growth and tissue maintenance. Plant proteins tend to have amino acid patterns that are less effective at building human tissue. But they can be made adequate by combining proteins from more than one source at the same meal.

For example, grains tend to be low in lysine but contain adequate amounts of methionine, while legumes are just the reverse. Eating them together balances the limiting amino acids and allows the body to produce the protein it needs. Adding just a small amount of animal protein improves the amino acid pool still further. This phenomenon, called ''the complementary value of proteins,'' has evolved in the diets of many cultures. In the Chinese meal, for instance, the large serving of rice protein is complemented in part by the protein in beans, and the mixture of amino acids is enriched still more by small amounts of poultry, beef or fish.

But essential amino acids are not the only players on the field. The remainder of our protein need is for the so-called ''non-essential'' amino acids. They are actually essential for life. But because they can be manufactured by the body from other amino acids, we have no particular dietary need for them.

Surveys have shown that in this country, protein deficiency is uncommon. It is most likely to be seen in chronic alcoholics, the elderly poor and in teen-age girls and women on certain fad diets. But most of us eat far more protein than we need. In the United States, about 15 percent of our total caloric intake is from protein. That amounts to about 100 grams a day, or 2 to 2.5 times our daily requirement.

Scientific perspective on protein requirements has changed little for several decades, and there is no evidence of widespread problems involving protein intake. Curiously, merchandising of protein and its components, amino acids, continues unabated. But our needs for protein can easily be met by diet, any additional amount conveys no special benefit.